<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <div id="box">
        <input type="checkbox">
        <span>两周内自动登录</span>
    </div>
    <div id="box2">
        为了您的信息安全，请不要在网吧或者公用电脑上使用此功能
    </div>
</body>
<script>
    //获取元素
    let zsc_box = document.getElementById('box')
    let zsc_box1 = document.getElementById('box2')
        //划入事件
    zsc_box.onmouseover = function() {
            zsc_box1.style.display = 'block'
        }
        //滑出事件
    zsc_box.onmouseout = function() {
        zsc_box1.style.display = 'none'
    }
</script>

</html>
<style>
    #box {
        width: 200px;
        height: 30px;
        margin: auto;
        text-align: center;
    }
    
    #box2 {
        width: 200px;
        height: 40px;
        border: 1px solid black;
        background: wheat;
        font-size: 12px;
        margin: auto;
        display: none;
    }
</style>